Generally, a typical electrical connector includes some form of dielectric or insulative housing which mounts a plurality of conductive terminals. The terminals have contact portions which are engageable by the contacts of a complementary mating connector or other connecting device. In most instances, the contacts of the mating connectors all engage simultaneously during the mating procedure.
On the other hand, there are applications wherein it is desirable to have certain contacts of the mating connectors interengage before other contacts. This type of application often is called a "first make-last break" system. For instance, it may be desirable for the contacts of a ground circuit to engage prior to the contacts of a "hot" circuit to prevent electrical "arcing" between the hot or live contacts.
Heretofore, one system for providing a "first make-last break" ability in a connector has been to simply provide selected terminals with longer contact portions than other terminals. Therefore, the selected terminals will be engaged prior to the other terminals and will be disengaged after the other terminals. A problem with such systems is that different terminal configurations must be fabricated and maintained in inventory which, in turn, is not particularly cost effective.
Another system for providing a "first make-last break" ability in a connector has been to provide identical terminals but to stagger the insertion depth of the terminals during assembly so that the contact portions of selected terminals are engaged before and disengaged after the other terminals. A problem with these types of systems is that different assembly steps must be used in fabricating a single connector, or elaborate assembly machines must be used. Again, such systems are not particularly cost effective.
In at least one other system for providing a "first make-last break" ability, disclosed in Japanese Patent Publication No. 3-13679, the extreme front tip of one terminal is blocked or protected by plastic material of the connector housing, whereas the extreme front tip of one or more of the other terminals is not blocked. Therefore, the tip of the one terminal will be engaged before the tip of the other terminals. Problems with this type of system are that the tips of the metal terminals may cause stubbing and damage to the mating contacts. In addition, full contact forces are not established immediately upon initial engagement with the exposed terminal tips which could affect the function of the first make-last break contacts. In essence, the control of the contact points with these types of systems is governed by the shape of the contacts, whereas the present invention provides control of the contact points by the location of the plastic material of the housing, which is typically easier to control.
The present invention is directed to solving the problems discussed above by providing a simple electrical connector which can utilize identical terminals yet afford a "first make-last break" ability in the connector.